I get it. Your trying to keep it simple and not into a
thing with all sorts of new equipment. I feel you. Tho I still say your better off bleeding couple gal of juice- not grapes. Afterwards anything extra not fitting in the carboy just stick in some bottles till you rack off the lees. Then use the bottle wine to top it up. The can discard the rest of ya don’t want any fussing over the extra. Simply put- If ya gotta toss, toss some juice. Not the grapes.
It’s a thoughtful offer. Just looking at the logistics of it for 18lbs might end up going to waste and could be much better served improving your wine. That is, unless someone lives close by and could benefit from a half lug Barbera. (Btw sounds like a great blend. Zin juice w/ barbera grape
)